my 3 hp 1994 yamaha 3mlhs intermitantly starts but wont run for more then a few seconds. i am in truuble a lot.i have two 3hp motor with the same problem ihave taken carbs apart on both, float valve working good. i have an internal 5 gal. fuel tank and just cant believe this would cause the carb boul to to go dry. which i think is the problem. help???